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Recyclation of dust from production of dry mortar blends
Ondrůšková, Nela ; Novotný, Radoslav (referee) ; Šoukal, František (advisor)
The work deals with the problem of disposal of ever-increasing waste (dust) from the production of building materials and examines the possibility of recycling dust dust into cement repair mortar. The aim of this work was to determine the composition of individual dust particles from the production of cement mixtures and to determine their mechanical properties, as well as to determine the ideal ratio of dust particles to each other when mixing the dust mixture and its mechanical properties. This mixture consisted mainly of dust from products based on Portland cement, aluminous cement, gypsum and lime hydrate. The mixture further replaced part of the cementitious mortar and the impact of the additive on the mechanical properties of the cementitious mortar was determined. X-ray fluorescence spectrometry was used to determine the elemental composition, and X-ray diffraction analysis was used to determine the mineralogical composition. Test specimens were prepared according to the ČSN EN 12390 standard. Mechanical strength tests were performed on the test specimens. A large part of the test specimens could not be subjected to mechanical tests because the test specimen did not solidify even after a long time. The individual measurements that could be made show that the mechanical properties of the dust samples show values which have shown that the dust cannot be recycled into the product due to its instability. Dust particles have too diverse composition and in combination with cementitious repair mortar do not have the required properties. The problem is especially the sampling from the data, which did not solidify at all and thus excluded the remaining samples with already good properties of the same sample. When designing the method of recycling, it was necessary to take into account which product of the company is most in demand, where recycling would also make economic sense, which is also an important indicator for the operation of the company today. Dust particles could prove successful in another product, but it would not be advantageous for the company now, so now the recycling of dust particles will not start and they will be further disposed of in the same way.
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Hybride binders based on the high-calcium ash
Hubáček, Václav ; Cába, Vladislav (referee) ; Koplík, Jan (advisor)
The goal of this bachelor´s thesis was to develop a hybrid binder based on high calcium fly ash with the focus on addition of Portland cement, observation of hydration process, measurement of mechanichal properties, identification of hydration products and comparation with Portland cement. Hybrid binder was developer by adding different amounts of Portland cement to the selected mixture of high calcium fly ash activated by sodium hydroxide. Setting times and flexural strength and compressive strength were measured for these hybrid binders. Afterwards one type of hybrid binder was selected for more analyses (XFR, XRD, SEM/EDS and isothermic calorimetry). These analyses were also used for a sample of Portland cement and alkali activated high calcium fly ash and afterwards these three samples were compared between each other. The collected data show that the compositions of the activated fly ash and hybrid binder are very similar and the addition of Portland cement to the mixture has only a minor impact. Main hydration product for both of them was ettringite. Addition of Portland cement to the activated high calcium fly ash has positive impact on mechanical properties, it shortens the start of setting time of a mixture and it also increases early and later compressive strenghts.
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The influence of hydration accelerators on cement doped with zinc
Beneš, Pavel ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
Zinc in cement has negative properties mainly due to a significant delay in hydration. This bachelor thesis deals with the study of hydration of cements containing zinc. The course of cement hydration was monitored by isoperibolic calorimetry. Zinc was doped to CEM I 42.5 R in the form of 1 weight percent zinc oxide. Calcium oxide, formic acid and calcium formate were used in various proportions as accelerators. The obtained results were compared with the measured strengths and finally the suitability of the given accelerators was discussed for use in construction application.
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The development of the solidification material from hybrid cement based on slag
Valach, Jakub ; Janča, Martin (referee) ; Koplík, Jan (advisor)
The bachelor thesis is focused on the research and development of hybrid cements based on slag. The base is granulated blast furnace slag, which serves as a substitute for cement, cement is used as an admixture. Various additions of cement and activator are monitored. The mixture is activated by Caustifying limestone. Firstly, the strengths of the mortars are mixed and measured without the addition of cement in order to find a suitable ratio of activator and slag. Subsequently, I focused on mixing and measuring the strength of mortars with the addition of Portland cement and I looked for suitable samples, which I analyzed by XRD, EDS, SEM. I also determined their stiffening time, lavish and volume stability.
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Study of alkali-silica reaction in hybrid systems
Bradová, Lada ; Bílek, Vlastimil (referee) ; Kalina, Lukáš (advisor)
This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.
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The study of zinc influence on Portland cement hydration.
Ptáček, Martin ; Janča, Martin (referee) ; Šiler, Pavel (advisor)
The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.
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Blast furnace slag as a component of hydraulic binders
Velebný, Josef ; Faltus, Miloš (advisor) ; Kuchařová, Aneta (referee)
The aim of this work is to evaluate blast furnace slag as an additive in hydraulic binders. These additives favorably affect the mechanical, chemical and phase properties of cements and binders on their basis. Basic structural and chemical analyzes of studied slags and reference cement and structural analyzes of hydrated binders were carried out on their basis. Furthermore, this thesis deals with testing and comparison of mechanical properties of mortar test bodies based on Reference Portland cement itself and with the addition of finely ground granulated and air cooled blast furnace slag and the development of these properties over time. Subsequently, these results are compared and made out about the usability of the studied materials for the production of hydraulic binders as compared to cements without added slag depending on time. Testing of mechanical properties according to the relevant standard ČSN EN 12390. Attention is paid mainly to the development of compressive strength and flexural tension. The XRD and XRF methods were used to study the phase and chemical composition of studied materials and hydrated binders based on these. Keywords: Slag, portland slime, hydraulic binder, Portland cement, blast furnace slag, phase composition, glass phase, latent hydraulicity, pozolanita, alkaline...
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